This invention relates to an accurate method for calculating the depth of a fishing bait presentation and a device for accomplishing that purpose.
Fishermen currently use electronic fish finders and electronic depth finders which show the location of schools of fish. Such devices use a sounding and sensing device fixed to the hull of the boat which emits any of a variety of wave forms and the reflection of such wave form is then sensed by the hull mounted sensing probe. The depth of the water that the boat is passing over is calculated based upon that reflection. Such devices are also capable by virtue of their resolution to determine if the solid object being sensed is true bottom or is actually a fish or school of fish. The results of such measurements are often visually displayed on a monitor inside the boat so that the fisherman can see a representation of the water's bottom and the actual depth where the fish are located.
Heretofore, however, the fisherman was unable to know where his bait presentation was in relation with the fish that he saw on his depth monitor and was only able to approximate his bait presentation in relation to the fish, and was further unable to re-position that line quickly so that the bait presentation was near the fish. Fishermen have heretofore used some sort of down rigger device for trolling behind the boat which device is merely a heavily weighted line played out at a predetermined depth through which the fishing line runs so that as the boat moves the downrigging would force the fishing line to trail behind the down rigging device at that predetermined depth. Such a device is difficult to rig and impossible to adjust quickly.
Devices have previously been designed which use a trigonometric function such as the device of Connor, U.S. Pat. No. 3,874,108. Such devices were cumbersome to read accurately and maintain and were not easily adjustable so that the fisherman could respond quickly to the conditions he observed on his fish finder device.